The present invention relates to a theft warning system, and more particularly to a theft warning system which issues a warning to protect vehicle contents when a vehicle door is opened without actuation of a door key.
Known theft warning devices will detect opening of one of the vehicle doors without actuation of a door key and issue a warning. Such a theft warning device is set to a warning condition when the door lock devices are in a locked state, or when all of the vehicle doors and the trunk are closed. If the device is in this set condition and one of the vehicle doors or the trunk lid is opened without a door key, the theft warning device determines that the vehicle is being broken into. Subsequently, based on this determination, the theft warning device will issue a warning signal to pulsate the vehicle horn, or repeatedly flash the vehicle headlights and taillights. Such a theft warning device is set to the warning condition even if a vehicle door is closed by a seated passenger. Hence, when the passenger opens a door to bet out, the theft warning device will activate, thereby generating alarm signals.